Corrugated metal tube for an external conductor or sheath of an electric cable

ABSTRACT

A corrugated metal strip is curved and transversely overlapped to form a tube, the corrugation being inclined relative to the transverse axis such that the edges have their corrugations axially offset by half a corrugation and the external zone in turn is axially offset by one half a corrugation to define an edge abutment determining the exact diameter of the completed tube.

1 51 June 6,1972

United States Patent Jocteur [5 References Cited UNITED STATES PATENTS [54] CORRUGATED METAL TUBE FOR AN EXTERNAL CONDUCTOR 0R SHEATH OF AN ELECTRIC CABLE [72] Inventor:

138/121 ...l38/l73 l38/l73 2,606,953 1,652,703 12/1927 Cushman.

Robert Jocteur, Lyon, France [731 Assignees Cable De Lyon Alsacienne, Lyon, France 221 Filed: Dec. 17,1970

21 Appl.No.: 99,205

Primary ExaminerMartin P. Schwadron Assistant Examiner-Ronald H. Lazarus Attorney-Sughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT A corrugated metal strip is curved and transversely over- [30] Foreign Application Priority Data Dec. 18, 1969 lapped to form a tube, the corrugation being inclined relative to the transverse axis such that the edges have their corrugations axially offset by half a corrugation and the external zone 51 l38/l2l,l22, 173,150,151, 138/154, 156; 72/368; 29/4773; 174 102 D, 102 R,

in turn is axially offset by one half a corrugation to define an edge abutment detemtining the exact diameter of the completed tube.

[58] Field of 4 Claims, 2 Drawing Figures PATENTEDJUH 6 1972 FIG FIG. 2

CORRUGATED METAL TUBE FOR AN EXTERNAL CONDUCTOR OR SHEATH OF-AN ELECTRIC CABLE BACKGROUND or THE INVENTION a 2. Description of the Prior Art A Means have already been proposed for obtaining a satisfactory application of these two overlap zones on one another.

For example it has been proposed, in a tube comprising pseudosinusoidal corrugations, the profile of which is constituted by an alternating succession of convex portions and concave portions, to give the convex portions of the external zone a larger radius of curvature than that'of the convex portions of the remainder of the width of the strip and consequently to give the concave portions of the zone a smaller radius of curvature than that of the concave portions of the remainder of the width of the strip.

Owing to this arrangement, the corrugations of the two zones readily overlap one another, and the internal zone cannot penetrate below the external zone over a greater length than that of the latter, since its edge comes to abut on the narrows of the corrugations at the place where the external zone is connected to the remainder of the width of the strip. The strip, therefore, cannot be wound on a smaller diameter than that which results from these arrangements.

It has further been proposed to produce tubes by means of a strip having triangular-profile corrugations. The external and internal zones of such a strip are satisfactorily applied against one another but no abutment defines the winding diameter of the strip.

SUMMARY OF THE INVENTION constitute the tube, the corrugations of the internal zone overlap perfectly in the corrugations of the external zone, and the edge of the said internal zone comes to abut at the discontinuity in the corrugations at the end of the external zone, since at this region the corrugations which thus come opposite one another are offset relative to one another by the amount of half a corrugation.

BRlEFDESCRIPIlON-OFTHE DRAWINGS Theaccompanying drawing show by way of example a flexible tube according to the invention comprising triangular-section corrugations.

FIG. 1 is a perspective view of the corrugated strip before it is curved, and

FIG. 2 is a perspective view of a section of tube produced by means of this stri DESCRIPTIO OF THE PREFERRED EMBODIMENT In these Figures, A designates,- the external lateral edge of the'strip, B the internal lateral edge, and C the line of discontinuity in the corrugations. 1

Between the edge A and the line C, the corrugations are progressively oflset by half a corrugation, that is to say by onehalf, and the corrugations on either side of the line C are also offset by half a corrugation. As a result, when the strip is wound to the form of a cylinder (FIG. 2) the corrugations of the edge A are in register with the corrugations of the edge 8 and are placed exactly on these, until they come to abut on the discontinuities of the line C; therefore, the amount of overlap cannot exceed a length greater than the distance L between the lines B and C.

It will be apparent that the invention is independent of the nature of the material of which the strip is made, which may be for example a bimetallic material, and also of the means used for assembling the two overlapping zones, which may include for example welding or the use of an adhesive substance.

The invention has as its object to provide a flexible tube, the

structure of which is different from these known structures.

This tube which comprises undulations or corrugations of anydesired profile, is characterized in that, on the one hand,

the direction of the corrugations is inclined relative to the I What is claimed is:

l. A flexible metal tube comprising: a wound corrugated strip forming a cylinder, the direction of the corrugations being inclined relative to the transverse axis of the strip such that the pitch is equal to one-half the width of a corrugation,

the corrugations of the strip intermediate of its overlapped edges being abruptly laterally oflset a distance equal to the width of a half corrugation, such that the valleys of one portion of the corrugated tube to the side of the demarcation line formed by the offset, are in alignment with the apices of the tube portion to the other side of said demarcation line.

2. The flexible metal tube as claimed in claim I wherein the overlapping zones are connected by welding.

3. The flexible metal tube as claimed in claim 1 wherein the overlapping zones are connected by means of an adhesive substance.

\ 4. The flexible metal tube as claimed in claim 1 wherein the strip is of bimetallic material. 

1. A flexible metal tube comprising: a wound corrugated strip forming a cylinder, the direction of the corrugations being inclined relative to the transverse axis of the strip such that the pitch is equal to one-half the width of a corrugation, the corrugations of the strip intermediate of its overlapped edges being abruptly laterally offset a distance equal to the width of a half corrugation, such that the valleys of one portion of the corrugated tube to the side of the demarcation line formed by the offset, are in alignment with the apices of the tube portion to the other side of said demarcation line.
 2. The flexible metal tube as claimed in claim 1 wherein the overlapping zones are connected by welding.
 3. The flexible metal tube as claimed in claim 1 wherein the overlapping zones are connected by means of an adhesive substance.
 4. The flexible metal tube as claimed in claim 1 wherein the strip is of bimetallic material. 